User Manual

Cabinet descriptionNortel Networks Confidential 1–13
S8000/S8002/S8006 BTS Reference Manual
There are four operational modes:
Low temperature –40°C (–40°F) <Tcab <15°C (59°F)
The heater is energised, the damper closed to the outside and air is recirculated
via the holes in the base of the cooling system.
Medium temperature 15°C (59°C) <Tcab < Ts
The heater is switched off, the damper remains closed and further heating of the
equipment enclosure is achieved solely by the internal equipment loading.
Normal temperature Tcab = Ts
The damper position is controlled automatically by the modulating motor,
mixing appropriate amounts of recirculated and external air to maintain a
constant temperature. Excess air is rejected from the cooling system from vents
either side of the cooling system.
High temperature Tcab > Ts
Although the damper is fully open, the cooling system is unable to keep the
cabinet temperature to Ts which now rises in sympathy with the external
temperature. At an outside temperature of 50°C (122°F), the internal cabinet will
rise to a nominal 60°C (140°F) under fully loaded conditions.
The cooling system is monitored by:
two hard alarm outputs:
• The first alarm output signals a fault on the cooling system,
• the second one indicates a maintenance requirement for the filter.
three alarm LEDs for on–site fault diagnostics.
• The red LED indicates critical alarm for fan failure.
• The yellow LED indicates critical alarm for heater circuit failure.
• The green LED indicates maintenance alarm for clogged filter.
On the top of the cooling system, there is a window in the lid which allows to
view the LEDs (see Figure 1–4). They are normally on when healthy and off on
alarm.
The cooling system is DC powered that allows internal or external battery back–up.
The dc power consumption of the cooling system is 400–450W. The cold start–up
performance of the unit is controlled by an inbuilt ac to dc converter (for operation
of the fans) and by a 2.5 kW heating element.